Theorem 3.1 (Khinchine-Kahane Inequality, via Szarek's proof, [1]} Theorem 5.20) 
Let \((B,|\cdot |_B)\)  be a normed vector space. Then for any \(p\in [1,+\infty ]\) , there exists a constant \(C_p\)  such that for any \(n\ge 2\)  and for any \(b_1,\cdots ,b_n \in B\) , we have
\(\mathbb {E}\left[\left|\sum _{i=1}^n b_i X_i\right|^p_B\right] \le C_p \mathbb {E}\left[\left|\sum _{i=1}^n b_i X_i\right|_B\right],\) 
